1. Field of the Invention
This invention relates to a protein regulating the sensitivity to an antimycotic aureobasidin and a gene coding for this protein, namely, a gene coding for a protein regulating aureobasidin sensitivity. The present invention further relates to a series of the uses of the protein and the gene. Furthermore, it relates to an antibody against this protein and the use of the same.
2. Description of Related Art
Systemic mycoses including candidiasis have increased with an increase in immunocompromised patients in recent years due to, for example, the extended use of immunosuppressive drugs and acquired immunodeficiency syndrome (AIDS), and as opportunistic infection due to microbial substitution caused by the frequent use of widespectrum antibacterial antibiotics. Although drugs for treating mycoses such as amphotericin B, flucytosine and azole drugs (for example, fluconazole and miconazole) are now used to cope with this situation, none of them can achieve a satisfactory effect. Also, known diagnostic drugs are insufficient. For candidiasis, in particular, although there have been known several diagnostic drugs (for example, CAND-TEC for detection of candida antigen and LABOFIT for detection of D-arabinitol),none of them gives any satisfactory results in specificity or sensitivity.
The reasons for the delay in the development of remedies and diagnostic drugs for mycoses as described above are that fungi causing the mycoses are eukaryotic organisms similar to the host (i.e., man) and thus not largely different from man and that knowledge of fungi, in particular, pathogenic fungi is insufficient. Therefore it is difficult to distinguish fungi from man or to selectively kill fungi, which is responsible for the delay in the development of drugs for mycoses.
Recently the application of genetic engineering techniques such as antisense or PCR to the treatment and diagnosis of mycoses has been expected. However known genes which are applicable thereto and/or proteins coded for by these genes are rare (PCT Pamphlet WO92/03455). Regarding pathogenic fungi, there have been cloned in recent years an acid protease gene, which has been assumed to participate in the pathogenicity of Candida albicans (hereinafter referred to simply as C. albicans) and Candida tropicalis (hereinafter referred to as C. tropicalis) causing candidiasis [B. Hube et al., J. Med. Vet. Mycol., 29, 129-132 (1991); Japanese Patent Laid-Open No. 49476/1993; and G. Togni et al., FEBS Letters, 286, 181-185 (1991)], a calmodulin gene of C. albicans [S. M. Saporito et al., Gene, 106, 43-49 (1991)] and a glycolytic pathway enzyme enolase gene of C. albicans [P. Sundstrom et al., J. Bacteriology, 174, 6789-6799 (1991)]. However, each of these genes and proteins coded for thereby is either indistinguishable from nonpathogenic fungi and eukaryotic organisms other than fungi or, if distinguishable therefrom, cannot serve as a definite action point for exhibiting any selective toxicity.
Aureobasidin [Japanese Patent Laid-Open No. 138296/1990, No. 22995/1991, No. 220199/1991 and No. 279384/1993, Japanese Patent Application No. 303177/1992, J. Antibiotics, 44 (9), 919-924, ibid., 44 (9), 925-933, ibid., 44 (11), 1187-1198 (1991)] is a cyclic depsipeptide obtained as a fermentation product of a strain Aureobasidium pullulans No. R106. It is completely different in structure from other antimycotics. As Tables 1 and 2 show, aureobasidin A, which is a typical aureobasidin compound, exerts a potent antimycotic activity on various yeasts of the genus Candida including C. albicans which is a pathogenic fungus, Cryptococcus neoformans, Histoplasma capsulatum, Blastomyces dermatitidis and fungi of the genus Aspergillus (Japanese Patent Laid-Open No. 138296/1990) but has an extremely low toxicity in mammal. Thus this compound is expected to be useful as an antimycotic being excellent in selective toxicity.
Hereinafter, Candida, Cryptococcus and Aspergillus will be abbreviated respectively as C., Cr. and A.
TABLE 1 ______________________________________ Test strain TIMM No. MIC (.mu.g/ml) ______________________________________ C. albicans 0136 .ltoreq.0.04 C. albicans var. stellatoidea 1308 .ltoreq.0.04 C. tropicalis 0312 0.08 C. kefyr 0298 0.16 C. parapsilosis 0287 0.16 C. krusei 0270 .ltoreq.0.04 C. guilliermondii 0257 0.08 C. glabrata 1062 .ltoreq.0.04 Cr. neoformans 0354 0.63 Cr. terreus 0424 0.31 Rhodotorula rubra 0923 0.63 A. fumigatus 0063 20 A. clavatus 0056 0.16 ______________________________________
TABLE 2 ______________________________________ Test strain TIMM No. MIC (.mu.g/ml) ______________________________________ A. niduians 0112 0.16 A. terreus 0120 5 Peniciliium commune 1331 1.25 Trichophyton mentagrophytes 1189 10 Epidermophyton floccosum 0431 2.5 Fonsecaea pedrosoi 0482 0.31 Exophiala wemeckii 1334 1.25 Cladosporium bantianum 0343 0.63 Histoplasma capsuiatuin 0713 0.16 Paracoccidioides brasiliensis 0880 0.31 Geotrichum candidum 0694 0.63 Blastomyces dermatitidis 0126 0.31 ______________________________________
Each of the conventional antimycotics with a weak toxicity shows only a fungistatic effect, which has been regarded as a clinical problem. In contrast, aureobasidin has a fungicidal effect. From this point of view, it has been urgently required to clarify the mechanism of the selective toxicity to fungi of aureobasidin. However this mechanism still remains unknown.
Under these circumstances, the present invention aims at finding a novel protein regulating aureobasidin sensitivity through the clarification of the mechanism of the selective toxicity to fungi of aureobasidin. Accordingly, the present invention aims at finding a gene coding for a protein regulating aureobasidin sensitivity, providing a process for cloning this gene and the protein regulating aureobasidin sensitivity which is encoded by this gene, further providing an antisense DNA and an antisense RNA of this gene, providing a nucleic acid probe being hybridizable with this gene, providing a process for detecting this gene with the use of the nucleic acid probe, providing a process for producing the protein regulating aureobasidin sensitivity by using this gene and providing an antibody against the protein regulating aureobasidin sensitivity, and a process for detecting the protein regulating aureobasidin sensitivity by using this antibody.